|Budget Amount *help
¥1,800,000 (Direct Cost : ¥1,800,000)
Fiscal Year 1994 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 1993 : ¥1,000,000 (Direct Cost : ¥1,000,000)
We have already found that an H-ras mutant, N116Y,exhibited a dominant negative activity toward normal ras function and was capable of inhibiting the ras-mediated signaling pathways. In this study, we demonstrated that N116Y inhibited the production of the active GTP-bound form of ras p21s. This suggests that N116Y may consume the guanine nucleotide exchange factors and inactivate the cellular ras function.
Next, we examined whether the N116Y mutant could suppress the growth of human tumor cells. N116Y extremely inhibited the proliferation of A431 (vulva), PC3 (prostate), T24 (bladder), MCF7 (breast), NKPS and TMK1 (stomach) cancer cell lines. A431 and PC3 cells were particularly susceptible to N116Y.In order to test the effects of N116Y on the neoplastic phenotypes, we transfected a less efficient N116Y expression vector into A431 cells. Almost all clo nes survived after G418 selection. However, they did not retain the N116Y gene and only one clone faintly expressed N116Y.This N116Y expressing clone had no tumorigenecity in vivo, and revealed deformed morphology and DNA fragmentation, suggesting that N116Y might have induced apoptotic cell death. Thus, N116Y may be applicable for gene therapy of a wide spectrum of human tumors.